Multi-walled placeholder

ABSTRACT

A placeholder for vertebrae or vertebral discs includes a tubular body, which along its jacket surface has a plurality of breakthroughs or openings for over-growth with adjacent tissue. The placeholder includes at least a second tubular body provided with a plurality of breakthroughs and openings at least partially inside the first tubular body. The first and second tubular bodies can have different cross-sectional shapes, can be are arranged inside one another by press fit or force fit or can be connected to each other via connecting pins and arranged side by side to one another in the first body.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.15/012,827, filed Feb. 1, 2016, which is a continuation of U.S. patentapplication Ser. No. 13/914,471, filed Jun. 10, 2013, now U.S. Pat. No.9,254,199, which is a continuation of U.S. patent application Ser. No.11/645,228, filed Dec. 22, 2006, now abandoned, which claims the benefitof and priority from U.S. Provisional Patent Application Ser. No.60/753,854, filed Dec. 23, 2005, and the benefit of and priority fromU.S. Provisional Patent Application Ser. No. 60/808,028, filed May 23,2006, the disclosures of all of which are incorporated herein byreference.

BACKGROUND

The present invention refers to a placeholder for implantation into ahuman or animal body, especially as a placeholder for vertebrae orvertebral discs, a method for manufacturing such a placeholder, and amodular system for such a placeholder.

Placeholders, especially for vertebrae or vertebral discs are known. Forexample, DE 19504867 C1 discloses a placeholder in the shape of acylindrical-tubular body with a plurality of rhombic or diamond-shapedopenings that are arranged in rows and columns. At the ends of thecylindrical tube are provided projecting serrations and recesses incorrespondence with the rhombi that serve for engaging with adjacentvertebrae or adjacent tissue. The diamond-shaped openings facilitatein-growth of the tissue into the implant, such that the latter may knitwell with the body.

Moreover, an implant is known from US 2005/0015154 which has ascaffold-like structure in which the latticework extends over the fullbody or through the entire body of the implant. Such integrallatticework structures are intended for use especially in replacementimplants for joints, such as hips, knee joints, shoulder joints and thelike. However, such integral latticework structures are difficult tomanufacture and have to be adjusted and manufactured individually tosuit every application case.

DE 101 38 079 AI discloses a placeholder of adjustable axial length inwhich two sleeve-like parts are arranged adjustably inside one another,more precisely via a lever arrangement over which the parts areconnected. Although this device facilitates very precise lengthadjustment, the lever arrangement is complicated to manufacture.

DE 198 04 765 C2 discloses a placeholder for insertion between twovertebrae with an adjustable axial length. The total length is adjustedby moving an external tube relative to an internal tube. The lengthadjustment proceeds stepwise by means of catches.

DE 697 19 431 T2 describes a longitudinally adjustable vertebral discplaceholder in which two sleeve bodies arranged telescopically insideone another are adjusted relative to each other and are lockable viascrew arrangements. However, this arrangement does not uniformlydistribute the load across the screw connections and does noteffectively allow in-growth by the surrounding tissue because of theclose arrangement of the sleeve bodies.

US 2003/0078660 discloses an implant that may be used as a placeholderin which the implant has a sleeve-like body that is corrugated. Thiscorrugated body may in turn be arranged inside a further sleeve body.However, the corrugated form of the one implant part again makes forcomplicated manufacture.

EP 09 047 51 AI describes a tubular support body for vertebrae havingtwo cages guided in one another which may be connected to each other bya projecting stud on the jacket surface of the one cage and axial feedchannels in the jacket of the other cage. With this arrangement,facilitating of latching positions at different depths is provided.However, the support body is limited in variability by the feedchannels.

Based on the above, there is a need for an implant which is easy tomanufacture and versatile in use, can provide load dissipation, allowsin-growth into human or animal tissue, and is suitable for use asplaceholder in the spine, that is, for vertebral discs and vertebrae,but also for tubular bones of the upper and lower extremities.

SUMMARY

According to one aspect of the present invention, several tubularbodies, namely a first tubular body and at least a second tubular body,are provided at least partially one inside the other, such that amulti-wall placeholder is formed which not only provides load-absorbingproperties but also is suitable for allowing in-growth of adjacenttissue. The cross-sectional shapes of the first and the second bodies ina cross-sectional plane transverse to the longitudinal axis of theplaceholder can be different. In particular, the second body arranged inthe first body can have a simple or basic geometric shape, namely, ashape which is easy to manufacture. Such shapes include cylindrical orcuboid shapes with round, oval, rectangular or triangularcross-sections. In addition, a shape having a constant cross-sectionalong its length may be used. Such simple geometrical basic shapes forthe first and second bodies may be used to generate suitable mechanicalproperties, yet are affordable and easy to manufacture.

The multi-wall placeholder described herein also provides a largecontact surface with the bone at the front face of the placeholder. Inaddition, with a preassembled multi-wall placeholder, a betteradjustment to the bone is possible. Consequently, subsidence of theplaceholder may be considerably reduced, if not completely prevented.This can be important for weak osteoporotic vertebrae. The placeholderaccording to the present invention may also include a plurality ofsecond tubular bodies nested inside each other, all of which are atleast partially disposed in the first tubular body.

In one embodiment, the first body may have a circular cross-sectionalshape, while the second body or bodies may have a triangular, square,hexagonal, octagonal or generally polygonal, oval or kidneycross-sectional shape.

In a further embodiment, the first tubular body, i.e., the external bodymay have a cross-sectional shape other than that of a circle, such as anoval or kidney cross-sectional shape, in which case the second body mayhave a correspondingly adjusted different cross-sectional shape, asdescribed above or a similar shape.

According to another aspect of the present invention, which is alsoapplicable to all disclosed aspects of the invention, several secondbodies may be arranged alongside each other in the first body.Accordingly, this arrangement can also achieve mechanical stabilityand/or ease of in-growth by the surrounding tissue into the placeholder.In addition, the wall thicknesses of the individual components, i.e. ofthe tubular bodies, may be kept small so as to facilitate in-growth ofthe tissue into the tubular bodies and thus into the implant.

By providing several second bodies in the first body, e.g., two or threesecond bodies, the wall thickness of the individual tubular bodies canbe reduced, while the overall loading capacity can be improved. Thearrangement of two, three or several second bodies in the first body isapplicable to all disclosed aspects of the invention.

The second bodies can be spaced from each other and/or from the firstbody to promote in-growth of body tissue between the bodies. This alsoallows for more precise adjustment relative to the adjacent bone or to aplaceholder end plate. Moreover, the spacing between the bodies willresult in better in-growth and a more homogeneous distribution of theload across the cross-section of the implant.

In the case of the arrangement of several second bodies in the firstbody, the arrangement of the second bodies may be such that theirlongitudinal axes are offset parallel to the tubular longitudinal axisof the first body. The result of this is that greater stability can beobtained for certain instances of mechanical loading. For example, theoffset arrangement of the bodies may lead to greater stability in thecase of flexural stress.

Overall, the cross-sectional shape of the first and/or second bodies mayassume diverse shapes, namely circles, triangles, oblongs, rectangles,squares, diamonds, (rhombi), polygons, hexagons, octagons, especiallywith rounded corners, ovals, kidney shapes or any free-form shapes.However, the shape can be restricted to certain basic shapes as thissimplifies manufacturability. Among the basic shapes are especiallycircles, triangles, oblongs, rectangles, squares, diamonds, hexagons,all angular shapes including those with rounded corners and ovals andkidney shapes.

According to a further aspect of the present invention, which is alsoapplicable to all disclosed aspects of the invention, the second body orbodies can be accommodated in the first body by means of a press fit orforce fit. For example, the outer dimension of the second body or bodiesis larger than the inner dimension of the first body. This results in anelastic deformation of the bodies in the case of a force fit or anadditional plastic deformation in the case of press fit. Alternatively,a connecting element or retaining element between the bodies can be aforce fit or press fit.

The press fit or force fit may thus be directly affected by contactbetween the first body and the second body/bodies or by the connectingelements.

Alternatively, according to a further aspect of the invention, theconnections between the bodies and/or connecting elements may take placeby means of friction, a material or a positive connection (form-fit).

According to another aspect of the present invention, which is alsoapplicable to all disclosed aspects of the invention, the placeholdercomprises a first tubular body having a jacket surface with a pluralityof openings for over-growth with adjacent tissue and a second tubularbody having a jacket surface with a plurality of openings, the secondtubular body disposed at least partially inside the first tubular body.At least one spacer may be used wherein the second tubular body isspaced apart with the at least one spacer from the first tubular body.The spacer may also take the form of a connecting element configured toconnect the first tubular body to the second tubular body.

In particular, the connecting elements may comprise retaining platesand/or connecting pins.

The retaining plates may be formed as plates or rings arrangedtransversely to the tubular longitudinal axis that are held by press fitor force fit or screw or rivet connections or generally by means offriction, a material or a positive connection (form-fit) in the firstbody. The second bodies may preferably also be held by press fit orforce fit or again by connecting pins or generally by means of friction,a material or a positive connection.

This means that the second bodies, for example may form a structuralunit with the connecting elements, which is then held overall by meansof a press fit or force fit in the first body.

The connecting pins may be formed as rivets, screws and/or bars, whichare welded, for example.

For arranging the second bodies in the first body, at least one, butpreferably several, and especially two retaining plates may be provided.The arrangement of the retaining plates may occur at the ends of thetubular bodies as end plates or distributed along the length of thetubular bodies as intermediate plates.

The retaining plates may have a plurality of openings as well, moreprecisely in addition to the receivers, by means of which the secondbodies are received and held. The plurality of openings again serves thepurpose of in-growth of adjacent tissue.

In addition or as an alternative to the retaining plates, connectingpins may be provided, which are formed especially as rivets, screwsand/or bars, which are, for example, welded.

The connecting pins preferably have stop faces for spaced retention ofthe bodies, for example a stop face may be provided by a correspondingrivet or screw head, while a second stop face may be provided in thevicinity of the thread or of the end of the rivet opposite the head.

The connecting pins may be arranged in the openings or breakthroughs inthe jacket surface of the tubular bodies which are provided for knittingwith adjacent tissue. Alternatively, separate connecting openings may beprovided for receiving the connecting elements in the tubular bodies orother components of the implant, such as the retaining plates.

In the case of screw connections, preferably the thread holes areprovided in the first outer body, such that the screw with its screwhead lies on the inside. This results in a smooth external side withoutprojections parallel to the tubular longitudinal axis.

According to a further aspect of the invention, which is also applicableto all disclosed aspects of the invention, the tubular bodies can bearranged at least partially inside each other and may be connected bymeans of detachable connecting means or connecting means attachable orconnectable directly at the point of use, such that a modular system iscreated, which facilitates in simple fashion individual adjustment torequirements. Accordingly, a modular system of several tubular bodiesand corresponding connecting means may be provided, with the surgeoncomposing the corresponding placeholders to suit individual needsdirectly at the point of use. Naturally, however, the placeholders mayalso be supplied ready-made. But, even here, changes may still be madein the case of detachable connecting means.

Additionally, a connection of the tubular bodies can be provided merelyat a few sites on the jacket surface and/or in the vicinity of the frontfaces, such that, when viewed along the full length of the placeholder,free space that is available for in-growth of tissue is created in wideareas between the placeholders. For example, the connecting elements maybe restricted to a total of 2 to 24, preferably 2 to 12 elements, and/or2 to 4, especially 3. In another embodiment, three connecting elementsmay be assigned to each row of openings or breakthroughs in the jacketsurface. The connecting elements may cooperate with the breakthroughsthemselves or with further receivers, recesses or holes, such as threadholes.

In a further embodiment, the tubular bodies may be arrangedconcentrically, such that parallel wall areas are formed, especially inthe case of the same cross-sectional shapes.

In yet another embodiment also applicable to all disclosed aspects ofthe invention, the connecting elements may preferably be variablyattached in the openings of the jacket surface of the tubular bodies,such that the tubular bodies may be arbitrarily aligned and arrangedrelative to each other. For example, the bodies can be arranged suchthat they are not completely inside each other, but to, for example,leave them projecting out in the longitudinal direction. This means thatthe length or height of the placeholders may be adjusted, since thedifferent tubular placeholders arranged inside one another may beretracted telescopically from each other or, conversely, pushed intoeach other in order for them to be subsequently fixed in this position.This is especially possible continuously or in steps. Additionally, thetubular bodies may also be rotated against each other, such that theopenings provided in the jacket surfaces are in alignment or staggeredrelative to, for example, one or two adjacent bodies or all bodies.

Also, the tubular bodies may have different forms, especially differentwall thicknesses, such that, for example, the external tubular body maybe very thin in order to facilitate rapid over-growth or in-growth bythe surrounding tissue through the openings, while the internal body orbodies have a greater wall thickness to impart stability to theplaceholder.

The different shapes which are possible for the cross-sectional shapesare also conceivable for the openings or breakthroughs in the jacketsurface of the tubular bodies, such that their external contour, too,may have the shape of a circle, a triangle, an oblong, a rectangle, asquare, a hexagon, an octagon, generally a polygon with or withoutrounded corners, a diamond or similar.

In all aspects, the tubular bodies may be arranged spaced apart fromeach other, with this space either provided by the connecting elementsthat connect the tubular bodies and/or separate spacers that may beprovided, especially on the inside and/or outside of the jacket surface,preferably in the shape of bars or plates projecting at right anglestowards the outside or the inside. On account of the spacing of thetubular bodies, sufficient space is available for in-growing tissue.Furthermore, on account of the spaced arrangement of tubular bodies,correspondingly broad contact surfaces may form at the ends or frontfaces that render separate attachment of end plates or similarunnecessary.

The tubular bodies may also have, at least on one end, or on both ends,projections and/or recesses which enable engagement with adjacentvertebrae or other tissue and facilitate in-growth.

The connecting elements, which may be formed by pins, bolts, catches,screws, end plates and similar, may be variably accommodated, especiallyat the openings or breakthroughs of the jacket surface, such that noadditional separate receivers need to be provided for the connectingelements. This can reduce outlay and simplifies manufacturability.Nonetheless, corresponding separate receivers may be provided at thejacket surfaces of the tubular bodies.

In a further embodiment, the placeholders have, at the front faces ofthe tubular bodies, at least one, preferably two end plates, whichsimultaneously serve as connecting means. The end plates, which, forexample, are annular, have for this purpose cut-outs and/or recessesinto which the projections at the ends of the tubular bodies may engage,especially positively and/or non-positively. The annular end plate mayfunction as a tensioning or spring-loaded ring that has a separating gapor slit, such that the projections provided in the cut-outs or recessesof the tubular bodies are held by means of friction by the end plate.

Correspondingly, the intermediate plates or retaining plates may also beformed generally as tensioning or spring-loaded rings.

Alternatively or additionally, it is naturally also possible to have abonded (material) connection of end plates or retaining plates andtubular bodies, such as by means of welding, especially laser welding,as also applies to the other connecting means, especially those providedin the vicinity of the jacket surfaces,

The tubular bodies and/or the connecting elements may be coated or havereceived a surface treatment. For example, coatings to be mentioned inthis regard are hydroxy apatite or plasma treatments, which, forexample, may lead to a rough titanium surface if titanium or titaniumalloys are used as material.

Overall, all suitable biocompatible materials having the correspondingproperties may be used for the various components, such as tubularbodies and connecting elements. Preferred are biocompatible polymers ormetals, such as titanium or titanium alloys, or also nitinol, anickel-titanium alloy. Especially, different materials may also be usedfor the various components.

According to a further aspect, the placeholder has at least twodifferent tubular bodies, for example, one body differing in diameterfrom the other. These bodies are arranged at least partially inside eachother, and the bodies are then connected to each other, preferablydetachably, by means of at least one connecting element. In this regard,the arrangement of the tubular bodies may be varied relative to eachother, e.g., along the longitudinal axis. This is especially true if theconnecting elements may be used at many locations along the tubularbodies. Additionally, the angle arrangement between bodies may bevaried.

Through the structure of the tubular bodies of the invention, which isdescribed in detail especially in the following embodiments, it is alsopossible to adjust the length and/or the alignment of the ends of thetubular bodies by means of cutting to length at any site, The result isa further increase in the variability of use.

Additionally, the placeholders may be coated or subjected to surfacetreatment not only altogether following assembly, but also individuallybefore the components are assembled. Accordingly, even in the case ofparts on the inside, such as a cylindrical tubular body arranged lyingon the inside, said body may be coated or surface treated prior toassembly, such that complete coating or surface treatment here mayoccur.

In another embodiment, the present invention provides a modular,individually usable system for placeholders, e.g., through the use ofindividual components, which can be used alone, preassembled orselectively assembled. The corresponding placeholder has an extremelylarge surface area due to its many walls and construction from severaltubular bodies, and thus markedly facilitates in-growth and on-growth.Additionally, despite the very large surface area, manufacturability isimproved and, in particular, coatability and surface treatability areimproved. This also results in improved in-growth properties. Inparticular, the modular assembly allows for individual surface treatmentof the single components. Thus, different coating of the individualcomponents may take place, i.e., of the various cylindrical-tubularbodies located in the different positions. This results in an implanthaving good mechanical stability and improved in-growth characteristics,which is especially suitable for vertebral discs or placeholders. Anoptimum fusion element for orthopedics is thus achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

Further, characteristics and features of the invention are apparent fromthe following description of preferred embodiments using the encloseddrawings. The drawings show in purely schematic form, in

FIG. 1 a first embodiment of a placeholder of the invention;

FIG. 2 a plan view of the placeholder from FIG. 1;

FIG. 3 a three-dimensional representation of a further placeholder ofthe invention with a detailed representation of the jacket surface;

FIG. 4 a plan view of the placeholder from FIG. 3;

FIG. 5 a three-dimensional representation of a third embodiment of aplaceholder of the invention;

FIG. 6 a plan view of the placeholder from FIG. 5;

FIG. 7 a perspective representation of the placeholder from FIG. 5without end plate;

FIG. 8 a plan view of the placeholder from FIG. 7;

FIG. 9 perspective representations of two individual tubular bodies andthe placeholder in the assembled state and plan views of the respectivetubular bodies;

FIG. 10 a perspective view of a further embodiment of a placeholder ofthe invention with a detailed view of the jacket surface;

FIG. 11 a perspective representation of a further embodiment of aplaceholder of the invention with a detailed view of the jacket surface;

FIG. 12 a perspective representation and a plan view of a furtherembodiment of a placeholder of the invention;

FIGS. 13 (a)-(c) a perspective representation, a lateral view and a planview, respectively, of a further placeholder of the invention;

FIG. 14 perspective representation of a further embodiment of aplaceholder of the invention;

FIG. 15 perspective representation of the embodiment of the placeholderfrom FIG. 14 in a shorter variant;

FIG. 16 a plan view of the placeholder in accordance with FIG. 15;

FIG. 17 a perspective representation of a further embodiment of theplaceholder of the invention;

FIG. 18 a plan view of the placeholder from FIG. 17;

FIG. 19 a perspective representation of a further embodiment of aplaceholder of the invention;

FIG. 20 a plan view of the placeholder from FIG. 19;

FIG. 21 a perspective representation of a further embodiment of aplaceholder of the invention;

FIG. 22 a plan view of the placeholder from FIG. 20;

FIG. 23 a perspective representation of a further embodiment of aplaceholder of the invention;

FIG. 24 a plan view of the placeholder from FIG. 23;

FIGS. 25 to 29 representations of cross-sectional shapes of tubularbodies for the present invention;

FIGS. 30 to 35 representations of the shapes of breakthroughs oropenings in the jacket surface of a placeholder or tubular body of theinvention;

FIG. 36 a perspective representation of a screw connection;

FIG. 37 a cross-sectional view of the screw connection from FIG. 36;

FIG. 38 a perspective view of a connecting pin as screw;

FIG. 39 a perspective view of a rivet connection;

FIG. 40 a cross-sectional view of the rivet connection from FIG. 39;

FIG. 41 a perspective representation of the rivet from FIGS. 39 and 40in the un-riveted state;

FIG. 42 a perspective representation of the rivet from FIG. 41 in theriveted state;

FIG. 43 a first example of a use of a placeholder of the invention in aschematic lateral representation;

FIG. 44 a further schematic lateral representation of a furtherembodiment for the use of a placeholder of the invention; and

FIG. 45 a lateral view of a third application example for the presentinvention.

DETAILED DESCRIPTION

FIG. 1 shows a perspective representation of a first embodiment of aplaceholder 1 of the invention in which the tubular bodies 2, 3 and 4are partially arranged inside each other.

The tubular body 4, which has the largest diameter, accommodates thetubular bodies 2 and 3 of smaller diameter. Tubular body 3, which hasthe next largest diameter, accommodates the tubular body 2 of thesmallest diameter.

The tubular body 3 is arranged in the tubular body 4, such that itprojects over the edge 5 of the tubular body 4 in the direction of thelongitudinal axis of the placeholder 1. Similarly, the tubular body 2 isarranged in the tubular body 3, such that it projects over the edge 6 ofthe tubular body 3.

The tubular bodies 2, 3 and 4 are connected to each other via pins 8(see FIG. 2), which are detachably inserted by press fit throughcut-outs or holes 25 (see FIG. 3) of the tubular bodies 2, 3, 4.Accordingly, it is possible, when the pins 8 have been removed, toadjust the length or height of the placeholder 1 by mutually pushing thetubular bodies 2, 3, 4 against each other along the longitudinal axis ofthe placeholder 1. At the desired length or height, the tubular bodies2, 3, 4 may be attached to each other and fixed in the correspondingposition by inserting the corresponding pins 8 into the holes 25.

The pins 8 may have corresponding stopping and/or catching means attheir ends, such as hooks (not shown), to ensure that pins 8 are securedin the holes 25. Additionally, other connecting means, such as screwswith threaded holes and the like, are conceivable.

The tubular bodies 2, 3, 4 have at their jacket surface 10 a pluralityof openings 9, which in the embodiment shown in FIG. 1, have a hexagonalshape and are uniformly arranged in rows and columns, such that agenerally honeycomb structure is produced. On account of this honeycombstructure, simple in-growth of tissue is ensured combined withsimultaneous stability and strength of the placeholder 1. Additionally,the weight of the placeholder 1 is reduced. Due to the multiple wallformation on account of the arrangement of tubular bodies 2, 3 and 4inside each other, in-growth of tissue is not hampered at least in theoverlapping regions despite increased stability and strength.

FIGS. 3 and 4 are a perspective representation (FIG. 3) and a plan view(FIG. 4) of a further embodiment of a placeholder 1 in accordance withthe invention, in which similar or identical parts are provided with thesame numerals.

The embodiment of FIGS. 3 and 4 differs from that of FIGS. 1 and 2essentially in that the tubular bodies 2, 3 and 4 are completelyaccommodated inside each other such that the tubular bodies 2 and 3 donot project beyond the upper edge 5 of the tubular body 4.

As a result, the edges 7, 6, 5 of the tubular bodies 2, 3 and 4 form acommon contact plane for, e.g., an adjacent vertebra. Due to the threetubular bodies 2, 3 and 4 being arranged inside each other, and beingspaced apart from each other, the result as compared to a single tubularbody, is a much greater contact surface in the form of a ring, withoutthe need to provide additional end plates or the like.

The ends of the tubular bodies 2, 3 and 4 of the embodiments of FIGS. 1to 4 each have projections in the form of projecting bars or spikes 11(referred to herein as projections 11) and indentations 12, such thatoverall corrugated edges 7, 6 and 5 result. The projections 11 and theindentations 12 can be made by cutting off or cutting to length thestructure of the tubular bodies 2, 3 and 4 perpendicular to thelongitudinal axis, and more precisely approximately in the middle of aseries of openings 9. Correspondingly, each indentation 12 has a shapewith parallel wall sections formed by the projections 11 and atriangular bottom, which connects the parallel wall sections.

The projections 11 and the indentations 12 engage with adjacent bodyparts, such as vertebrae or adjacent tissue and permit over-growth withcorresponding tissue.

Moreover, the detailed representation of FIG. 3 shows the holes 25 orreceivers for the pins 8 for connection of the tubular bodies 2, 3, 4.Instead of the pins 8 and holes 25, screws and threaded holes could alsobe used.

In FIG. 4, it may be seen that the concentrically arranged tubularbodies 2, 3 and 4, which are each formed as a cylinder in theembodiments of FIGS. 1 to 4, are spaced apart from each other and heldby individual, thin bars 13, which, in turn, are radially spaced apartfrom each other by a certain angle. In the embodiment shown in FIG. 4,the bars 13 are radially spaced apart from each other by an angle of120°.

In contrast to the pins 8, which may be detachable and/or attachabledirectly during the surgery involving the placeholder 1 of theembodiments of FIGS. 1 and 2, the bars 13 may have a solid bondedconnection (material connection) for example by means of laser welding,with the tubular bodies 2, 3 and 4, such that the placeholder isready-made.

FIGS. 5 to 8 show in various representations a further embodiment of aplaceholder 1 in accordance with the invention, which, like theembodiments of FIGS. 1 to 4, may especially be used as placeholders forvertebrae. Here, too, identical or similar components are provided withthe same reference numerals.

The embodiment of FIGS. 5 to 8 has, as especially shown by FIG. 8, twotubular bodies 3 and 4, which are arranged with tubular body 3completely accommodated in the tubular body 4.

The embodiment of FIGS. 5 to 8 differs from the embodiments of FIGS. 1to 4 in that, at each of the upper and lower ends, an end plate 14 inthe shape of an annular disc is provided, which is subdivided by a slitor gap 16. Moreover, several rectangular cut-outs 15 are arrangedannularly in the end plate 14. Accordingly, as particularly shown fromthe plan view of FIG. 6, the cut-outs 15 accommodate the projections 11of the tubular bodies 4 and 3.

Due to the slit 16, the annular end plate 14 functions as a tensioningor spring-loaded ring. For example, the width of the gap 16 can beelastically reduced by squeezing the ends 17 and 18 together when theend plate 14 is arranged. Due to the elastic recovery forces of theannular end plate 14, on being released after placement on the tubularbodies 3 and 4 and the insertion of the projections 11 into the cut-outs15, the end plate 14 relaxes, with the projections 11 being squeezed andpressed against the edges of the cut-outs 15. Thus, the end plate 14 isheld against the projections 11 non-positively or by friction.

Support of this kind is also possible for retaining plates that are notarranged at the ends of the tubular bodies but positioned along thelength of the tubular bodies at locations intermediate the ends of thetubular bodies.

FIGS. 7 and 8 show the placeholder 1 of FIGS. 5 and 6 in arepresentation without the end plates 14. Here it may be seen that thetubular bodies 3 and 4 are kept spaced apart merely on account of theend plates, without the need for additional connecting elements orspacers.

FIG. 9 shows a further embodiment of a placeholder 1 in accordance withthe invention, with the tubular bodies 3 and 4 initially shownindividually and, in the right sub-figure, in the assembled state. Asidefrom the perspective representations, the lower part of FIG. 9 shows theplan views of the tubular bodies 3 and 4. Again, identical or similarcomponents are provided with the same numerals, as in the previousembodiments.

While the external tubular body 4 essentially corresponds to theprevious embodiments, the inner tubular body 3 additionally has spacers19 in the form of plates, which project perpendicularly outwards inseveral rows on the jacket surface 10 of the tubular body 3. The spacers19 may either be formed integrally with the cylindrical body 3 orattached to it by means of bonded (material), positive (form-fit) ornon-positive (frictional) connection, Naturally, it is also conceivablefor the spacers 19 to be similarly provided on the inside of theexternal tubular body 4 or on both tubular bodies 3 and 4.

The individual spacers 19 are radially spaced around the circumferenceof the tubular body 3 at a specific angle, more precisely, in theembodiment shown in FIG. 9, each at an angle of 40°. Naturally, more orfewer spacers 19 may be arranged around the circumference or in a row,more or fewer rows and also at different distances.

In the embodiment shown, the spacers 19 may also be used simultaneouslyas connecting elements between the tubular bodies 3 and 4, for exampleby corresponding catch, interlocking or clip connections. This ispossible, for example, if corresponding cut-outs are provided on theinside of the tubular body 4 into which the spacers 19 may engage. Forexample, the dimensions of the inner diameter of the tubular body 4 andthe outer diameter of the tubular body 3 with the spacers 19 may bedesigned such that the outer diameter of the tubular body 3 with thespacers 19 is slightly greater than the inner diameter of the tubularbody 4, such that one or both of the bodies 3 and 4 is elasticallyextended or compressed, respectively, during assembly and relaxationthen occurs when the spacers 19 engage with the corresponding cut-outsor recesses (not shown) on the inside of the tubular body 4 in order tosimultaneously act as connecting elements.

FIGS. 10 and 11 show further embodiments of placeholders in accordancewith the invention, and find application, for example, in the case of orfor replacing vertebral discs. Here again, identical or similar partsare provided with the same numerals.

FIGS. 10 and 11 illustrate especially by way of the enlarged detailedviews of the jacket surface 10 that the tubular bodies 3 and 4 may bealigned differently, more precisely on the one hand such that theopenings 9 are flush or aligned with each other, as shown in FIG. 11,or, offset, as shown in FIG. 10. In an offset arrangement of theopenings 9, the bar-like regions of the mantle jacket I0 of the innertubular body 3 may be seen behind the opening 9 of the external tubularbody 4, whereas the bar-like regions of the jacket surface I0 ⁴ of theexternal tubular body 4 partially cover the opening of the tubular body3.

In contrast, in the case of the flush alignment of openings 9 of thetubular bodies 3 and 4, the jacket surface region I0 ³ of the innertubular body 3 is arranged behind the jacket surface region I0 ⁴ of theexternal tubular body 4 and a through-opening 9 is created in the jacketsurfaces 10 of the bodies 3 and 4.

FIG. 12, in turn, shows a placeholder for vertebrae that essentiallycorresponds to the previous embodiments and thus has the same numeralsfor identical or similar components.

In the placeholder 1 of FIG. 12, the tubular bodies 2, 3 and 4 are againinserted in each other, the particular feature here being that thetubular bodies 2, 3 and 4 have different wall strengths or thicknesses,as is especially evident in the plan view in the right sub-figure ofFIG. 12. Thus, the inner and outer tubular bodies 2 and 4 are thinnerthan the central tubular body 3. Thus, the central tubular body 3contributes the most to strength and stability, while the outer andinner tubular bodies 4 and 2 facilitate rapid in-growth and over-growthdue to the low wall thickness. Spacers, such as pins 8 or bars 13, arenot shown herein for illustration purposes.

FIG. 13 shows in the three sub-views (a) to (c), a perspective view (a),a lateral view (b) and a plan view (c) of a placeholder 1 for avertebral disc. Here, again, identical or similar components areprovided with the same numerals, as in the previous embodiments.

The embodiment of FIG. 13 corresponds to the placeholder 1 of FIG. 3,the difference being that just two tubular bodies 3 and 4 are providedand that only a single row of completely formed openings 9 is provided.Correspondingly, the height or length of the placeholder 1 of FIG. 13 ismarkedly reduced relative to that of the placeholder 1 from FIG. 3. Thiscorresponds to the different use purposes, namely on one hand to serveas placeholder for vertebrae (FIG. 3) and on the other to be used asplaceholder for a vertebral disc (FIG. 13).

FIG. 14 shows in a further embodiment a perspective view of aplaceholder in accordance with the invention in which again identicalnumerals are used for the same or similar components, as in the previousembodiments.

The placeholder 1 in FIG. 14 has a first, tubular body 4 with acylindrical tubular shape, which in turn possesses a plurality ofdiamond-shaped openings 9, which are arranged in rows and columns toform a honeycomb structure. The diamond-shaped openings 9 are limited bybars 10, which, as in the previous embodiments, form projections 11 andrecesses 12 at the upper and lower edge at the ends of the cylindricaltubular body 4.

In the external tubular body two retaining plates 30 are arranged, thatare provided in the end regions of the tubular body 4. The retainingplates 30 are completely accommodated in the tubular body 4 and are heldthere by press fit or force fit. Correspondingly, the outer diameter ofthe retaining plates 30 is chosen somewhat larger than the innerdiameter of the tubular body 4, such that the parts are elasticallytensioned. Other suitable means to secure the retaining plates may alsobe used.

The circular, disc-shaped retaining plates 30 have a plurality ofopenings 31, which facilitate in-growth and permeation by tissue.

Additionally, receiving openings 32 are provided in which second,cylindrical-tubular shaped bodies 3′, 3″ and 3′″ are accommodated, whichin their shape and form correspond to that of the external tubular body4. However, the second tubular bodies 3′, 3″ and 3′″ differ with regardsto their dimensions, i.e. the diameter of the second tubular bodies 3′,3″ and 3′″ is chosen much smaller than that of the external tubular body4. The receiving openings 32 of the retaining plates 30 are arranged atthe corner points of an imaginary triangle (shown in FIG. 16 with dashedlines), such that the second tubular bodies 3′, 3″ and 3′″ areaccommodated side by side to each other in the interior space of theexternal tubular body 4. The tubular longitudinal axes of the secondtubular bodies 3′, 3″ and 3″, which run through the center of thecircular cross-section of the second tubular bodies 3′, 3″ and 3″, aretherefore offset parallel to the longitudinal axis of the externaltubular body 4.

The second tubular bodies 3′, 3″ and 3′″ are also accommodated by pressfit or force fit in the receivers 32 of the retaining plates 30. Theouter diameter of the second tubular bodies 3′, 3″ and 3′ is thus againchosen somewhat greater than the diameter of the receiving openings 32,such that, on insertion of the second tubular bodies 3′, 3″ and 3″,elastic deformation of the second tubular bodies 3′, 3″ and 3′″ and ofthe retaining plates 30 occurs, which effects the press fit of thetubular bodies 3′, 3″ and 3′″ in the receiving openings 32.

While the embodiment of FIG. 14 may be used as a placeholder forvertebrae, the variant shown in FIG. 15, also in a perspectiverepresentation, is intended as a replacement for vertebral discs.Correspondingly, the placeholder 1 of FIG. 15, in which again identicalor similar components are provided with identical numerals as in theprevious embodiments, is chosen much smaller in length. Correspondingly,only a single retaining plate 30 is provided, instead of the tworetaining plates of the embodiment of FIG. 14. The retaining plate 30 inthe embodiment of FIG. 15 is arranged approximately in the middle of theheight of the placeholder.

Other than the differences described herein, the embodiment of FIG. 15does not differ from that of FIG. 14.

FIG. 16 shows a plan view of the embodiment of FIG. 15 in which thearrangement of the external tubular body 4 and of the second, innertubular bodies 3′, 3″ and 3′″ is clearly shown. Further, the openings31, which are provided in the retaining plates 30 for in-growth andpermeation by tissue, are shown. The openings 31 may have differentsizes as shown.

Overall, with the embodiments of FIGS. 14 to 16, an implant orplaceholder is provided which, on account of the chosen press fit orforce fit arrangement, is readily manufacturable and whose componentsfacilitate simple and variable arrangement. Additionally, sufficientfree space for in-growth by tissue to the external tubular body 4 isprovided by the arrangement of the tubular bodies 3′, 3″, and 3′″. Atthe same time, however, sufficiently large contact surfaces on the endsof the placeholder 1 are provided for accommodating and dissipatingload.

FIGS. 17 to 24 show different embodiments in which, without use of aretaining plate, several or individual second tubular bodies 3 ofdifferent shapes are accommodated in differently shaped external tubularbodies 4, again by press fit or force fit.

In the embodiment which, in FIGS. 17 and 18, is shown in perspective andplan view representations, respectively, the external tubular body 4has, in a cross-sectional plane perpendicular to the tubularlongitudinal axis, i.e. perpendicular to the jacket surface, a kidneyshape, whereas the second tubular bodies 3′, 3″ and 3′″ accommodated inthe external tubular body 4 have a circular cross-section.Correspondingly, the second tubular bodies 3′, 3″ and 3′″ areaccommodated side by side to each other in the external tubular body 4.

In the case of the placeholder 1, which, in FIGS. 19 and 20, is shown inperspective and plan view representations, respectively, two cylindricaltubular bodies 3′ and 3″ which have a circular cross-section arearranged, also by press fit or force fit, in an external tubular body 4with an oval shaped cross-section, whereas, in the embodiment of FIGS.21 and 22, three second bodies 3′, 3″ and 3′″ with cylindrical tubularshape, i.e. circular cross-section, are arranged in an external tubularbody 4 having a cylindrical-tubular shape and thus also circularcross-section.

In FIGS. 23 and 24 is shown a further embodiment of a placeholder 1 inaccordance with the invention in which, again, only two tubular bodiesare arranged inside each other. In the embodiment shown in FIGS. 23 and24, the inner tubular body 3 has a triangular shape in a cross-sectionrunning perpendicular to the tubular longitudinal axis, whereas theexternal tubular body 4, in turn, possesses a cylindrical tubular shapewith circular cross-section. In the embodiment shown in FIGS. 23 and 24,thus only one tubular body 3 is accommodated by press fit or force fitin the tubular body 4.

In the variant shown in embodiments of FIGS. 17 to 24, it would also bepossible, instead of press fit or force fit, to provide a connection forthe first and second tubular bodies 4 and 3 at their contact surfaces bymeans of connecting elements, such as connecting pins in the form ofscrews or bonded (material) connections, such as welding.

FIGS. 25 to 29 show different cross-sectional forms of tubular bodies 2,3, 4 of the kind that may be used in the present invention. Aside from acircular or annular cross-section, such as shown in FIG. 25, oblong,especially rectangular and preferably square shapes (FIG. 26), hexagonalshapes (FIG. 27), oval shapes (FIG. 28) or kidney shapes (FIG. 29) areconceivable. Additionally, there is the possibility of using othershapes, such as octagonal base shapes or totally free-form shapes.Preferred, however, are simple base shapes. Especially, it is alsopossible to combine cylindrical tubular bodies having differentcross-sectional shapes with each other.

FIGS. 30 to 35 show different shapes of openings 9 and their mutualarrangement in the jacket surfaces 10 of the tubular bodies 2, 3 and 4.Aside from the diamond shape (rhombus) of FIG. 30, circular shapes (FIG.31), oblong shapes, especially square and rectangular (FIG. 32),hexagonal shapes (FIG. 33), oval shapes (FIG. 34) or octagonal shapes(FIG. 35) are conceivable. Additionally, other suitable shapes areconceivable that facilitate a large area for the openings 9 combinedwith simultaneous stability of the interlaying framework.

As far as the mutual arrangement of the openings 9 is concerned, thesemay either be arranged in rows, in which the openings 9 are totallyspaced apart in rows, such as in FIGS. 32 and 35, or the openings arearranged in the rows such that they project into the correspondingcavities formed by openings 9 of adjacent rows, as is particularlypronounced in the FIGS. 30 and 33.

This also shows that the openings 9 in the columns in which they arearranged may be provided directly beneath each other or, preferably,offset from each other, such that axial load dissipation, especially,improves. As FIGS. 30 to 35 further show, the columns with openings 9arranged under each other may be each offset essentially from each otherby the half-width of an opening.

FIGS. 36 to 42 show in different views embodiments of connections bymeans of connecting pins, such as rivets and screw connections.

FIG. 36 shows a partial section of the jacket surface 10 or of the barsforming the jacket surface 10 of tubular bodies 3 and 4, in which ascrew connection is provided. The screw 13 has a screw head 40 which, asshown in a cross sectional view in FIG. 37, with a contact surface 43makes contact with the inner surface of the tubular body 3, while theshaft 45 of the screw 13 projects through an opening in the wall of thetubular body 3 and with its screw end 41 opposite the head 40 engageswith the threaded hole 42 of the external tubular body 4. In thisconnection, the contact surface 44, which limits the screw thread 41,makes contact with the inside of the external tubular body 4. The screwconnection is designed such that preferably the outside of the tubularbody 4 flushes with the thread-side end of the screw 13.

FIG. 38 shows the screw 13 in a perspective representation. Although notshown, the screw head may be configured to provide engagement with anactuating tool, such as a screw driver.

In similar representations as the screw connection, FIGS. 39 to 42illustrate a rivet connection. Here, too, the rivet connectionrepresents the connection between the tubular body 3 and the tubularbody 4, as may especially be seen in the perspective representation ofFIG. 39. With its contact surface 56, the head of the rivet 50 touches,as may be seen in FIG. 40, the inside of the tubular body 3, while thecontact surface 57, which limits the rivet section at the end of therivet 50 opposite the head 51, touches the inside of the externaltubular body 4. The tubular bodies 3 and 4 each have one through-holeopening, through which rivet 50 with the rivet shaft 52 is inserted. Therivet area 53 has a cylindrically shaped cut-out 55, such that,following insertion of the rivet 50 through the through-hole opening ofthe tubular body 4, the edge 54 may be crimped such that a reliableconnection is afforded and the rivet is prevented from leaving thethrough-hole opening of the tubular body 4.

FIGS. 41 and 42, each show the rivet 50 in the unriveted state (FIG. 41)and riveted state (FIG. 42) with edge 54.

FIGS. 43 to 44 are schematic lateral or sectional representations ofapplications for placeholders in accordance with the invention, with theplaceholder 1 in FIG. 43 serving as a replacement vertebral disc and theplaceholder 1 in FIG. 44 serving as a replacement vertebra.

The placeholders 1 in the applications of FIGS. 43 and 44 are part of aspinal column stabilization system, in which pedicle screws 20,especially polyaxial screws, are arranged in vertebrae, whichaccommodate between them a connecting rod 21 to mutually align andstabilize the spine.

Because of the arrangement in the spine, the placeholders 1 for thespine or vertebral discs are exposed to stresses, especially dynamicstress. The placeholder 1 according to the present invention, and inparticular, the multi-wall configuration and/or the multi-componentformation thereof, provides a solution for dealing with the notedstresses.

Additionally, the placeholder in accordance with the invention may alsobe used for clinical applications, such as long bones, e.g. following abreak, as shown in FIG. 45, in which in case of destruction of the bone22 in its central area, the arrangement of a corresponding placeholder 1of the invention and stabilization with a nail 23 and a screw 24 mayserve to reproduce the bone structure.

1-52. (canceled)
 53. A placeholder for implantation in a human or animalbody, the placeholder having a first end, a second end, and alongitudinal axis extending through the first and second ends, theplaceholder comprising: an inner wall defining an inner cavity extendingalong the longitudinal axis, wherein a plurality of openings are definedby and extend through the inner wall; an outer wall positioned aroundthe inner wall, wherein a plurality of openings are defined by andextend through the outer wall; and a connecting portion connecting theinner and outer walls and keeping the inner and outer walls spaced apartfrom one another in a direction transverse to the longitudinal axis,wherein the openings in the outer wall extend into the space between theinner and outer walls, and the openings in the inner wall connect thespace between the inner and outer walls with the inner cavity, topromote in-growth of body tissue; wherein the connecting portions isseparable from the inner and outer walls, and wherein when the inner andouter walls are connected to one another by the connecting portion, theconnecting portion extends into both the inner and outer walls and has awidened portion positioned in the inner cavity.
 54. The placeholder ofclaim 53, wherein the connecting portion comprises a screw or a rivet.55. The placeholder of claim 53, wherein the widened portion of theconnecting portion forms a stop configured to abut the inner wall whenthe inner and outer walls are connected to one another by the connectingportion.
 56. The placeholder of claim 55, wherein the connecting portioncomprises a second stop configured to abut the outer wall to maintain aconstant spacing between the inner and outer walls.
 57. The placeholderof claim 53, wherein the outer wall comprises an engagement structurefor engaging the connecting portion when the inner and outer walls areconnected to one another by the connecting portion.
 58. The placeholderof claim 57, wherein the engagement structure comprises a threaded holein the outer wall.
 59. The placeholder of claim 53, wherein when theinner and outer walls are connected to one another by the connectingportion, the widened portion is positioned in the inner cavity, while anopposite end of the connecting portion extends entirely through theouter wall and past an outer surface of the outer wall.
 60. Theplaceholder of claim 53, wherein the placeholder comprises a pluralityof the connecting portions to connect the inner and outer walls to oneanother.
 61. The placeholder of claim 53, wherein the outer wall isspaced apart equidistantly from the inner wall along at least a portionof a perimeter of the inner wall.
 62. The placeholder of claim 53,wherein the placeholder comprises a vertebral implant, where the firstand second ends are configured to contact vertebrae.
 63. The placeholderof claim 53, wherein the inner and outer walls each comprises titanium.64. A placeholder for implantation in a human or animal body, theplaceholder having a first end, a second end, and a longitudinal axisextending through the first and second ends, the placeholder comprising:an inner wall defining an inner cavity extending along the longitudinalaxis, wherein a plurality of diamond-shaped openings are defined by andextend through the inner wall; an outer wall positioned around the innerwall, wherein a plurality of diamond-shaped openings are defined by andextend through the outer wall; and a plurality of connecting portionsarranged at a plurality of different axial positions along thelongitudinal axis to connect the inner and outer walls and to keep theinner and outer walls spaced apart from one another in a directiontransverse to the longitudinal axis, wherein the openings in the outerwall extend into the space between the inner and outer walls, and theopenings in the inner wall connect the space between the inner and outerwalls with the inner cavity, to promote in-growth of body tissue;wherein at least one of the openings in the inner wall is aligned withone of the openings in the outer wall, such that a pathway having adiamond-shaped profile corresponding to the at least one opening in theinner wall extends entirely unobstructed from the inner cavity throughthe inner and outer walls to an outside of the placeholder.
 65. Theplaceholder of claim 64, wherein a plurality of pathways havingdiamond-shaped profiles corresponding to respective ones of the openingsin the inner wall extend entirely unobstructed from the inner cavitythrough the inner and outer walls to the outside of the placeholder. 66.The placeholder of claim 64, further comprising a third wall positionedaround the outer wall, wherein a plurality of diamond-shaped openingsare defined by and extend through the third wall, and wherein thepathway having the diamond-shaped profile extends unobstructed from theinner cavity through the inner wall, the outer wall, and the third wallto the outside of the placeholder.
 67. The placeholder of claim 64,wherein at least two of the openings in the outer wall are alignedlaterally at a same axial position along the longitudinal axis, andwherein at least two of the openings in the outer wall are at differentaxial positions.
 68. The placeholder of claim 64, wherein in a planetransverse to the longitudinal axis, the outer wall has an oblongcross-sectional shape.
 69. The placeholder of claim 64, wherein theinner cavity is open at both the first and second ends of theplaceholder.
 70. The placeholder of claim 64, wherein the space betweenthe inner and outer walls is open at both the first and second ends ofthe placeholder.
 71. The placeholder of claim 70, wherein at least partof the space between the inner and outer walls extends unobstructedbetween the first and second ends of the placeholder.
 72. Theplaceholder of claim 64, wherein the outer wall is spaced apartequidistantly from the inner wall along at least a portion of aperimeter of the inner wall.
 73. The placeholder of claim 64, whereinthe placeholder comprises a vertebral implant, where the first andsecond ends are configured to contact vertebrae.
 74. The placeholder ofclaim 64, wherein the inner and outer walls each comprises titanium.